Experimental Jet Parts in Carbon Fiber

We have some compressor blades that we will be testing in one of our LM1500s. It's the industrial version of the J79 turbojet, which powers the F-104 Starfighter, the F-4 Phantom II, and many other aircraft.

These blades are made from highly compressed carbon fiber and resin composite, with some finish machining to alter their shape.
Let's hear your comments and ideas...

Videos of the running test are coming up.

[C-M-E]

This is exactly how I ended up spiraling into graphene production two years ago, when I started R&D on composite hot end parts for my 200mm jet engine project. I tried both blisk and individual bladed versions, but they definitely need to be bonded onto a metallic leading edge and mounting base. Thermal expansion with the composite is fractions of a percent vs metallic, but they don't fare well with small particle impact. I was also trying some really wild designs to optimize the smaller size as that was more practical for my space, but I'm definitely interested to see how a full size application works out.

[HeliNerd]

Whatever your name is, you are awesome. Please keep the excruciatingly detailed videos coming, I've learned more about gas turbines from your videos than any other non literary resource. Thank you.

[josh]

Very interesting project improving the designs of these earlier jets. Thanks for both yourself and the customer for allowing this to be shared publicly

[ronnieprater]

I worked on the USAF J79 -15 engines and found your description of the testing very interesting. Looking forward to future videos. Great idea if the blades can take the stresses.

[Indiskret]

Fascinating! Sharing this with us is very generous of you and very much appreciated.

[danirizary]

Innovation makes me happy and recharges my optimism.

[jdrissel]

Many years ago I interviewed at a company that made first stage fans for the engines for a Learjet. They made most of it out of carbon fiber but the leading edge had an inset piece of a very high nickel stainless steel. It was so ductile it was hard to cut. They actually modified a paper cutter to cut the stuff because ordinary tin snips would just smear it. I suspect you're going to need to do the same on this project at some point. I seem to recall that the alloy was something like 15% nickel, which is a huge amount of nickel for a stainless steel.

[russcole]

Just thinking out loud here, if there is 21 blades on the hub, why not test three carbon blades spaced evenly around the hub.

[volvojohn]

Wouldn't it produce the same results mounting that hub on a shaft inside a spare front engine housing and spinning it up with a motorcycle engine or electric motor instead of risking damage to a very expensive working engine? I always enjoy your videos Jay, thanks

[inothome]

Hey man, nice shirt! I wear mine when it gets chilly here and I get so many compliments on it, seriously. I don't think they realize it's an FR workshirt.
Good song too.

[dtiydr]

I just still wonder why this haven't been done before, have always wonder this and now finally, finally I see it.

[thereddufus]

AgentJayZ, do you know if those blades are thermoset (epoxy resin) or thermoplastic (PEKK, PAEK, etc)? In the composites industry today thermoplastics are very much the new hotness because they can generally take more heat and are much faster to produce than thermosets (if you can reliably produce them). It is hard to tell via a video, but they look like a close compression molded discontinuous fiber thermoplastic part, probably with a continuous fiber reinforcement in the middle, which is in many ways an even cooler thing than 'just' a carbon fiber compressor blade. If that is the case, then those things really are bleeding edge technology. Very very cool, thank you for showing us.

[scott]

I hope you get to show us all of it as well!

[stormeagle]

Strange test... very good when it works, but I wouldn't do that on a running engine, because if these blade break off, they will be ingested into the engine and also create imbalances... I think this will cause major damage to the engine. I would try to spin this as a single compressor stage by some other engine, if it takes a really high amount of power, then maybe by the power turbine of a two-spool engine. If it breaks, it might shred the compressor stage, but there will be no damage to an entire engine.

[felixar]

When air enters a widening path, it slows down. That’s intuitive. Like a river slowing down when it’s wide and getting faster when it’s narrow.

Well, energy is being conserved, so if the air slows down, it both heat up and gets compressed.

If the path is **too** wide tho, or if it just exhaust into open air, the air will expand, and therefore speed up and cool down.


And when the air is already supersonic everything is reversed somehow.

This is how a converging diverging nozzle manages to accelerate the gases twice.

The get accelerated to supersonic in the converging part, and they expand and get accelerated even more in the diverging part

[volvojohn]

I would imagine the stainless blades stay relatively straight under load at 7500 rpm because of centrifugal force (helicopter rotor blades are a perfect example) but, I think at 100 grams, 7500rpm they will bend back and loose most of their pitch from lack of weight. (getting late and I find this very interesting) good luck

[flyonbyya]

How is the carbon fiber blade bonded to the root, or is the entire piece all carbon fiber?

[nixie]

Someone is putting serious money into that testing, because should the blades fail...it will be an interesting teardown of a complete engine.

[nhwilkinosn]

This morning I was reading the Wikipedia pages on the rb211 and the Trent. First of all, I did not know Rolls Royce named their engines after rivers in England, but second, that each turbine blade removes 740 horsepower from the gas steam. That really helped me understand and visualize how much power the engine as a whole produces, but the forces the blades have to handle. Imagine an internal combustion engine where each cylinder produces 740 horsepower. That would be almost 6, 000 horsepower from an 8 cylinder. I think the only thing that comes close to that is top fuel.

Then on top of that, there's the fuel consumption. With typical jet fuel, it's easy for me to imagine tens if not hundreds of gallons per minute being sprayed through a nozzle, pumped via pumps. Sure, you just have to have a big ol fuel tank, big ol lines, and a pump that can keep up. Pumping a room temperature liquid is pretty straight forward. Then you mentioned running on propane. That's a LOT of propane to be moving. It's a lot of jet fuel to be moving too, don't get me wrong, but that's A LOT of propane. I've run propane lines to big houses and generators for the top 1%ers on lake Washington. Many of whom are world renown. A 3 or 4 inch gas main and the house has multiple 100k plus btu boilers isn't uncommon, and plumbed for over a million btu. I bet those gas lines couldn't even idle an lm1500. I'm going to have to go back and find the video where you talk at least a little bit about your propane setup, I think I have more appreciation for just how much fuel those drink

[daynosdr]

Who are these guys? I run a composites shop and ave been toying about the idea of pursuing something similar. Best of all, up here in Canada.